Such prestressing units are used in transmissions of motor vehicles in order, in particular, to permit a friction clutch in the drive train of a motor vehicle to be activated.
German patent DE 10 2005 053 555 B3 discloses an axial adjustment device in the form of a ball ramp arrangement. The axial adjustment device comprises two disks which are centered on a common axis, one of which is supported axially and the other can be displaced axially, and at least one of which disks can be driven in rotation. The two disks each have an equal number of ball grooves running in the circumferential direction on their end faces facing one another. The two disks are therefore mounted with balls as rolling bodies.
U.S. Pat. No. 5,485,904 likewise discloses a prestressing unit whose ramp disks are arranged such that they can rotate with respect to one another by means of balls as rolling bodies.
Likewise, U.S. Pat. No. 5,620,072 discloses a prestressing unit for a multidisk clutch whose ramp disks are also arranged such that they can rotate with respect to one another with balls as rolling bodies.
German patent DE 10 2004 015 271 B4 discloses a torque transmission device. Here, the rolling bodies and the axial bearing are mounted on a pitch circle which has the same diameter. Balls are used as the rolling bodies.
An axial prestressing unit is also used for prestressing multidisk clutches of the superimposition stages in the bevel differential gears.